The present invention relates to a gear unit for converting a fast, drive-side rotational movement that is limited in both directions into a slow rotational movement on the output side.
U.S. Pat. No. 5,105,672 discloses a unit of this general type, in which a force-transmitting element in the form of at least one cable is provided between the drive and the output.
It is an object of the invention to provide a gear unit that operates without play, and has a good synchronization characteristic, with an output that only fluctuates slightly when the input rpm remains unchanged, and with which positions can be determined and/or torques or forces can be detected.
In accordance with the invention, this object is accomplished by a gear unit for converting a fast, drive side rotational movement that is limited in both directions into a slow rotational movement on the output side, the unit being characterized in that the force-transmitting element acts on a one-piece, pivotably-seated intermediate part that is divided into two segments, with a position sensor being associated with an inside segment of the intermediate part, or a torque sensor being provided between the two segments of the intermediate part.
Thus, the gear unit of the invention, a force-transmitting element acts on a one-piece intermediate part that is divided into two segments and seated to pivot. A position sensor is allocated to an inside segment of the intermediate part, and/or a torque sensor is disposed between the two segments of the intermediate part.
In accordance with a preferred modification of the invention, the intermediate part comprises the inside segment and an approximately U-shaped outside segment that partially surrounds the inside segment. A slot that extends in an approximate U-shape is provided between the two segments. Furthermore, the two legs of the U-shaped outside segment are thinner than a center part that connects these two legs to one another.
In accordance with a preferred embodiment of the gear unit of the invention, a cable, band or the like is provided as a force-transmitting element between the drive and the output; and the two ends of the element are secured to the pivotably-seated intermediate part. The cable extends against the outer sides of the intermediate part, and is wound once or multiple times around the shaft of the drive, preferably in the form of an electric motor, for transmitting a drive moment.
In accordance with a further preferred embodiment of the invention, the force-transmitting element is a frictional wheel that is provided at the drive shaft and rests, in a frictional lockup, against the outer surface of the outside segment of the intermediate part, the surface being provided as a frictional surface. In a further preferred embodiment of the gear unit of the invention, the force-transmitting element is a toothed wheel that is secured to the drive shaft and is in a non-positive engagement with a toothing that is embodied on the outer segment and corresponds to a toothed rack.
According to the invention, on one side of the inside segment, an opto-electronic, position-sensitive detector is associated with the position sensor that is associated with the inside segment of the intermediate part, and a light source is provided on the other side. Between these, a slot that extends with a radially changing (e.g., spiral-shaped) course is provided in the inside segment. The shapexe2x80x94for example, a spiralxe2x80x94of the slot is selected such that a linear connection is formed between an angular change in the intermediate part and the displacement of the light beam on the detector.
Also in accordance with the invention, a torque sensor is or can be provided at the two segments of the intermediate part. An opto-electronic, position-sensitive detector that serves as a torque sensor is mounted in the center of a center part of the outside segment. On the other side of a slot embodied between the inside and outside segments, a slotted screen is mounted to the inside segment directly opposite the detector; a light source is disposed behind this screen.
According to the invention, therefore, a mechanical gear is produced, which converts a fast rotational movement of the drive that is limited in both directions into a slow rotational movement of the output, the transmission being effected without play and with a good synchronization characteristic. According to the invention, a sensor mechanism in the form of the position sensor and/or the torque sensor is integrated into the gear unit, the former generally determining the position and/or the latter measuring the torque of the drive or output. In the present invention, one or both of the two optical sensors is or are directly integrated into the gear unit in an especially compact manner.
Because of the special design of the U-shaped outside segment, the electro-optical, position-sensitive detector which operates as a torque sensor and is mounted in the center of the outside segment can detect a bending in the two legs of the U-shaped outside segment, which act like bending girders that are clamped on one side; this bending corresponds to the torque that is applied in the drive or output direction, respectively, and from which a corresponding force can be calculated in a known manner. Thus, a force-reflecting sensor mechanism is created, with which the force that is decisive in any type of tactile processes can ultimately be detected.